The need for detecting nitro-aromatic based chemical compounds, such as nitrotoluene, dinitrotoluene and trinitrotoluene (TNT), is to avoid spread of contamination in ground water that has leached these chemicals in areas where TNT has been disposed of or inadvertently lost.
U.S. Pat. No. 4,108,604 issued to Hiller on Aug. 22, 1968, discloses in a first embodiment, a method for analyzing water for TNT comprising the steps of allowing water to flow over a resin that contains quaternary ammonium groups and is coated with a flourescent dye, and then observing a change in fluorescence of the fluorescent dye. There is no indication of the level of concentration that can be detected by this method and no apparatus is disclosed.
U.S. Pat. No. 5,157,261 filed May 28, 1991 having some common inventors with the instant invention discloses an apparatus for detecting TNT in air. That patent (U.S. Pat. No. 5,157,261) has a common assignee, the United States Department of Energy. The above mentioned application uses a significantly different sensing device. It has a chemically treated fiber optic distal tip for sensing TNT molecules in air which is drawn into the sensor by a vacuum pump.
The present apparatus provides a simple, portable device that detects TNT in water utilizing a simple method and giving accurate results in the parts-per-billion range in a matter of minutes.